The present invention relates to compositions and methods for stabilizing particulates in subterranean formations over a wide temperature range. More particularly, the present invention relates to integrated consolidation fluids and methods of using integrated consolidation fluids to consolidate particulates within a subterranean formation.
Hydrocarbon wells are often located in subterranean formations that contain unconsolidated particulate matter that can migrate with mobile fluids within the formations such as oil, gas, or water. The presence of particulate matter, such as sand, in the produced fluids is disadvantageous and undesirable in that the particulates may abrade pumping and other producing equipment and reduce the fluid production capabilities of a producing formation. Unconsolidated areas within a subterranean formation include those that contain loose particulates that are readily entrained by produced fluids and those wherein the particulates making up the zone are bonded together with insufficient bond strength to withstand the forces produced by mobile fluids within the subterranean formation.
One method of controlling unconsolidated particulates involves placing a filtration bed of gravel near the well bore in order to present a physical barrier to the transport of unconsolidated particulate matter with the production of hydrocarbons. Typically, such so-called “gravel packing operations” involve the pumping and placement of a quantity of a desired particulate into the unconsolidated formation adjacent to the well bore. Such packs are time consuming and expensive to install. Weakly consolidated formations also have been treated by creating fractures in the formations and depositing proppant in the fractures wherein the proppant is consolidated within the fractures into hard, permeable masses using a resin composition to reduce the migration of particulates. In some situations the processes of fracturing and gravel packing are combined into a single treatment to stimulate hydrocarbon production while inhibiting particulate matter production with an annular gravel pack. Such treatments are often referred to as “frac pack” operations.
Another method used to control particulate matter in unconsolidated formations involves consolidating unconsolidated subterranean producing zones into hard permeable masses by preflushing the formation, applying a hardenable resin composition, applying a spacer fluid, applying an external catalyst to cause the resin to set, and applying an afterflush fluid to remove excess resin from the pore spaces of the zones. Such multiple-component applications, however, may be problematic. For example, when an insufficient amount of spacer fluid is used between the application of the hardenable resin and the application of the external catalyst, the resin may come into contact with the external catalyst in the well bore itself rather than in the unconsolidated subterranean producing zone. When resin is contacted with an external catalyst an exothermic reaction occurs that may result in rapid polymerization. The polymerization may damage the formation by plugging the pore channels, may halt pumping when the well bore is plugged with solid material, or may even result in a downhole explosion as a result of the heat of polymerization. Likewise, using these conventional processes to treat long intervals of unconsolidated regions is often not practical due to the difficulty in determining if the entire interval has been treated with both the resin and the catalyst. Also, the temperature of the subterranean formation may hamper the ability of the hardenable resin to cure. Hence, multiple hardenable resins may be needed depending on the subterranean formation's temperature at the region being treated.